Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
There's a way to do it that should only cause a subsecond "blip". Whether that calls for planned downtime its up to you.
Assuming you're running a fast STP variant, define a new Etherchannel trunk, using one more more links. Connect it. When you do, STP might block the new trunk or block the old trunk.
Once the new Etherchannel trunk is connected. You can disconnect or shut the original trunk. When you do, STP might migrate to the new Etherchannel, if it had not already done so.
If you wish, you might be able to define the original trunk link to join the new Etherchannel trunk.
